In order to dye nylon/cotton blended fabrics in solid colors with only acid dyes, a hetero-bifunctional bridge compound (DBDCBS) was examined. The bridge compound was designed to react only onto cotton fabrics first, on which amino-containing acid dyes react later by covalent bonding. By the effect of DBDCBS, amino-containing acid dyes exhibited high affinity toward the cotton fabrics. From the dyeing properties examined at various conditions, the optimum dyeing was decided at pH 4 and $100^{circ}C$. Consequently, the solid color was obtained on nylon/cotton blended fabrics in one bath dyeing process using only acid dyes. The DBDCBS did not show any negative effect on nylon side in terms of dyeing and physical properties.